* Replace :focus styles with :focus-visible
* Remove :active / .active styles
* Don't apply :hover styles for `.btn` that follows a `.btn-check`
This removes a large part of the visual confusion of button checks/radios - that you currently have to move your mouse away from them to see what they actually changed to (checked or unchecked)
* Reintroduce :active, but *not* for button checks/radios
* Sort focus styling specifically for button checks/radios
don't change background on focus, just give it the border/outline. again, avoids confusion whether something is checked or not while focused
* Re-add `outline:0` which was lost when resolving last merge conflict
Co-authored-by: Mark Otto <markd.otto@gmail.com>
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